Year	Percent
1983	10.8861
1985	9.4607
1987	7.44
1988	7.3467
1989	6.7697
1990	5.6026
1991	5.5731
1992	4.0385
1993	5.3263
1994	6.5358
1995	6.097
1996	5.2049
1997	4.3236
1998	3.3579
1999	2.6936
2000	2.1673
2001	1.8144
2002	2.2965
2003	3.4338
2004	4.3313
2005	4.4439
2006	3.5306
2007	2.798
2008	2.534
2009	3.369
2010	4.3988
2011	4.6016
2012	5.4697
2013	7.1922
2014	7.1347
2015	6.5259
2016	5.5728
2017	4.4761